1. Field of the Invention
This invention relates to a paddle used to improve forward propulsion of conventional kayaks, and specifically, the invention refers to a hydro-impelled paddle whose design allows the use of water patterns to generate forward propulsion during the full paddling process: from insertion in the water, pulling and extraction or retrieval out of the water.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
The kayak, invented by Eskimo hunters, is a long narrow water vessel that allows fast displacement in rough or calm seas, by means of a paddle that sinks alternatively on both sides of the kayak, and is pulled backwards to attain forward propulsion. The paddle as has been used for centuries is a board with variable length and extremes flattened, with a width of less than 4″ and a thickness less than 2″, and gradually rounded towards the center or shaft to about 1¼ for hands placement and comfortable handling. The flat extremes or blades have two functions: to cut the water when immersing and taking out the water, and to power the boat forward, once it is deep by offering resistance to the pulling action. The action of immersing and taking out the paddle will have no effect on impelling the boat forward. The entry and exit are two necessary steps to get the blade deep where force is done.
The action of traditional paddles is exclusively based on water resistance against the flat cross section of the blade when pulled parallel to the longitudinal axis of the kayak, but opposite to the motion direction. In this way water is used as a support or resistance surface for propulsion. Nevertheless, around the blade there are eddies and turbulences exiting the side walls, resulting naturally in power loss.
Europeans copied the kayak scheme, but not the traditional paddles, developing paddles made with an almost 6 feet shaft and two wide, flat, concave or spoon shaped blades on the extremes. They are made of wood, or a metal shaft and plastic blades or fiberglass reinforced plastic or carbon reinforced plastic, on either shaft and/or blades. Among improvements, some paddles are made with some asymmetry with respect to the shaft axis.
The most important innovation is the so called “Lituanian paddle” described in U.S. Pat. No. 4,737,126 (Lindeberg, et al. 1988), consisting of wing shaped euro blades, so as to get higher water grip and power. The blade design has the leading edge rounded and the trailing edge sharpened, with a convex frontal or “reverse” face and a concave back or “power” face.
The effect achieved by Lindeberg's paddle is so notable that it became the Olympic standard, and all modern competing paddles use this principle, with only small variations on the curved shape or tilting with respect to the shaft axis. The “Euro modified Paddle” or “Wing Paddle”, once immersed in the water, with the blade in an almost vertical position, travels horizontally and perpendicular to the boat displacement. The motion is horizontal after immersion, starting by the front of the boat and as close as possible to the hull, and emerging by the user's hip, two or three feet away from the boat. Looking from above it appears as an inverted V, with the tip in front of the boat and the open side by the waist, alternating sides in the paddling action. The effect of the wing blade traveling horizontally away from the boat, with an almost vertical shaft, is to propel the boat forwards.
All the motion and effect of the Wing Paddle is unidirectional. The blade enters the water fast, and is displaced sideways and the exit is at the end of that trajectory.
The mentioned Wing Paddles are not useful for those who paddle using the Greenland style with long thin narrow paddles and flat blades. Greenland paddles use the flat and sharp edge to cut the water and immerse deeply, close to the kayak hull. Once in the bottom the flat cross section serves to power the boat still close to the kayak, and when the pulling action is finished the paddle must exit from the bottom slicing the water with the sharp edge. Motion is decomposed in three stroke sections: Insertion to depth, pulling, and retrieval from bottom.
Lindeberg's paddle could perform the first two motions, if user wanted to use it in that way, entry to depth using the curved leading side, pull at the bottom with certain torsion due to the asymmetry of the blade placed with its maximum cross-section pushing against the water, but paddle extraction would not be possible. The reason being that the sharp edge would become the leading edge and the convexity on one side and concavity on the other creates turbulence and forces a violent rotation of the paddle with the consequence of loss of speed and stability.